1. Field of the Invention
The present invention relates generally to a power supply circuit for headlamps mounted on automotive vehicles. More specifically, the invention relates to a power supply circuit in which a pair of headlamps can be selectively connected to a power source in series or parallel so as to decrease or increase luminous intensity thereof.
2. Description of the Prior Art
Such a power supply circuit is described in the Japanese Utility Model First Publication (Jikkai) Showa No. 59-118648. This circuit comprises a pair of headlamps, a battery, a manually operable switch and a relay which can selectively establish the communication between the battery and the headlamps in series or parallel. In this circuit, the headlamps are connected to the battery in parallel via the relay when the switch is OFF so that luminous intensities of the headlamps are relatively high. In response to turning ON of the switch, the headlamps are connected to the battery in series via the realy, so that the intensities can be decreased. In this case, the headlamps can not be turned on if the connection in the relay is bad.